This invention relates to aquarium filters, and more particularly to bottom aquarium filters which can be positioned above the gravel bed in an aquarium tank.
One of the most commonly used type of aquarium filters is the bottom aquarium filter which is positioned in the tank above the gravel bed, such as shown in U.S. Pat. No. 2,782,161 and my U.S. Pat. Nos. 3,477,580 and 3,630,367. These filters contain filtration material to remove aquarium sewerage and convert contaminated water into decontaminated water which is then sent back to the tank. At the same time, an air stream is sent into the filter's air lift tube to circulate the flow of water into and out of the filter, as well as to aerate the water, whereby the filter becomes both an aerating as well as a filtering device.
One of the problems of bottom aquarium filters concerns the proper arrangement and retention of the filtering material within the filter. Typically, the bottom aquarium filter includes a container which stores the filtering material. However, in order to ensure a sufficient flow of water into the container and to provide adequate circulation of the water through the container, various compartments are formed for specific purposes within the container. For example, a separate compartment is usually provided for taking in or receiving the contaminated water. Then, this water passes through the filtering material which is in another compartment of the container.
A problem also exists in connection with the quantity of filtering material placed within the container. When the filtering material, such a polyester floss, is initially placed in the container, it is dry and fluffy with a lot of air space between the filaments. As a result, it is very compactable and occupies a large amount of space within the container where the polyester floss must be compressed to be an effective filtering material. Subsequently, when the filter is inserted into the aquarium tank, the compacted filtering material becomes wet and traps air bubbles therein, where the trapped air bubbles cause the material to float upwardly, thus blocking free flow of the contaminated water into the filtration compartment.
In many aquarium filters, the carbon of the filtering material is used as weight to prevent the filter from floating up from the bottom of the tank. However, due to improved modern day activated carbon, less carbon is required where one ounce of carbon granules can actually contain the equivalent of seven acres of adsorbent surface area. Additionally, this new type of carbon is lighter in weight than previously used carbon. Therefore, other means such as using gravel or even marbles must be used in order to weight the filter, where this other material is usually placed in the filtration compartment for lack of a better place, thus reducing the effectiveness of the filtration compartment.
An additional problem concerns proper distribution of the water through the filtering material. Once the water enters the container, it typically will pass through a small section of the filtering material and will not be evenly distributed through the filtering material. As a result, while one section of the filtering material becomes heavily contaminated and clogged with debris, other parts of the filtering material are hardly used. Nevertheless, because of the contaminated small area of filtering material, it will be necessary to throw out all of the filtering material and replace it, even though most of it is hardly used. Furthermore, the heavily contaminated section of the material does not provide a proper environments for aerobic bacteria which are helpful in filtering the contaminated water.
Other problems also exist with present types of bottom aquarium filters. For example, the bottom aquarium filter typically fits on top of the gravel bed. As a result, it is visible within the aquarium tank and its size and location become of importance with respect to aesthetics as well as to the capacity of the tank. It is desirable to have the filter occupy as small an area of the tank as possible, and preferably positionable in a rear corner of the tank for unobtrusiveness. Furthermore, since the aquarium filter must occasionally be taken out of the water in order to replace the filtering material, it is desirable to provide a handy means for pulling the filter out of the water without having it become disassembled accidentally by itself, yet provide sufficient ease for the user to disassemble it in order to replace the filtering material.
With prior art bottom aquarium filters, the size was so tall that it was very obtrusive in the tank. Furthermore, when pulling the bottom aquarium filter out of the water, it was either necessary to manually hold the filter together or risk the possibility that the parts may open up in the water while being removed. Some prior art devices trying to prevent such accidental disassembly in the water, made secure locking mechanisms to hold the parts of the filter together. However, it then became exceedingly difficult to disassemble the filter in order to replace the filtering material. On the other hand, some prior art filtering devices tried to maintain ease of disassembly to replace the filtering material, but they then risked accidental disassembly of the filter when in the water.